Wireless communications systems have made great advances in recent history, now offering near wireline communications system data rates, excellent reliability, low deployment costs, high degree of mobility, and so forth. With such a long list of advantages, wireless communications systems and attendant users are expected grow at a faster rate than ever before.
One form of wireless communications system is a heterogeneous network (HET-NET). A HET-NET may include communications controllers of differing power. For example, a HET-NET may include a system of macro cells that operate at high power levels, a system of low power cells, such as pico cells and relay nodes, which operate at reduced power levels. The macro cells and the low power cells may be part of a planned network operated by one or more operators of the wireless communications system. A HET-NET may also include a system of ad-hoc nodes, such as femto cells, Home eNBs, and so on. The ad-hoc network may be user deployed communications controllers that a user may add in order to improve performance in a small area, such as a home, an apartment building, a business, or so forth. Collectively, the communications controllers (macro cells, low power cells, ad-hoc nodes, and so on) may be referred to as nodes without loss of generality.
A HET-NET may be considered to be a multi-layer communications system, with the macro cells making up a first layer, and the low power cells making up a second layer. A HET-NET with multiple relay nodes may offer the following benefits: lower power transmission (less power consumption and less electromagnetic pollution), enhanced coverage and capacity at low cost, and flexible deployments.
Packet (information) delivery over a wireless communications system faces the same set of challenges like wireline communications but with additional wireless specific challenges. The challenges include:                Geographically co-located nodes from multiple network layers may present co-channel interference across different system layers (macro, micro, pico, and so forth, layers);        Scalability of operations, administration, and maintenance (OAM): a significant number of low power nodes may make it more complicated to perform OAM for the nodes;        Scarce radio resources;        Dynamic loading changes;        Frequent mobile handovers;        Severe security challenge;        Power/battery life restrictions; and        Dynamic topology.        